Put 5W20 in by mistake - should I change it?

Cool. About 6 km from where I work. If they are "good enough" or better, I'll take it there. Perhaps I'll just lower my oil level and send some of that in for giggles.

Yeah, I went to Canadian Tire today and the easy choice is 5W-30. $39 for 4.4L, sometimes with an extra litre bonus. Works for me, and exactly what the owners manual recommends.

I was a committed 10w30 buyer previously, just because it was so common and average and worked in every temperature I expected from Canadian winter to summer.

 

I have used Blackstone, but make no claims that they are superior to their competiion. Just like the 'family business' aspect of their web site. In fact, it's fair to mention a discussion at BITOG some time ago that Blackstone's numbers might not be so accurate. The right (though costly) way to know is to send replicate samples to several labs and blind duplicates to the same lab. No Prius operator has stepped up to the plate on that one.

 

That might be true in the GTA and perhaps Vancouver. Otherwise, especially in NW Ontario, Manitoba, and Saskatchewan, it's far too thick for cold winter operation